Process of treating rubber and the improved age resisting rubber produced thereby



. ing. In carrying the invention into practical Patented Aug. 22, 1 933I PROCESSO I TREATING RUBBER AND THE IMPROVED AGE RESISTING RUBBERPRO-DUCED THEREBY Hugh Mills Bunbury, Prestwich, and John Stanley HerbertDavies, Orumpsall, and William Johnson Smith Naunton, Prestwich,England, assignors to Imperial Chemical Industries Limited, aCorporation of Great Britain No Drawing. ApplicationOctober 31, 1931,Serial No. 572,436, and 1930 in Great Britain November 22,

6 Claims. (CI. 18-50) This invention relates to a novel process ofproducing age-resisting rubber of desirable prop-'- erties and to theproduct of such processes.

Many substances have heretofore been used or 5 suggested aspreservatives of rubber and been found for one reason or anothertobe'unsatisfactory in use. As examples of such compounds are certainhydroxy aromatic compounds, namely, certain phenols and naphthols. Thepresence of phenols or naphthols in a rubber mix generally retards thevulcanization or the compounds are apt to volatilize out of the rubber,which naturally does not obtain the benefits of their initial presence.Moreover, their employrubber-like substances and synthetic rubber) at asuitable stage in the manufacture thereof, a boric acid ester of anaphthol. This results in increasing the resistance of the rubber andrubher-like substances to deterioration due to ageefiect, we prefer toincorporate the boric acid ester of a naphthol in the rubber at the timethe mix is prepared, that is, prior to vulcanization. The proportionused is preferably'about 1% of the whole mix, but more or less may beused if so desired. j I

Our invention is illustrated but not limited by the following example,in which the parts-are by weight: g I I Ezvample A rubber mix is made upas follows:

Parts Pale crepe 100 Zinc oxide Chalk 100 Sulphur 3.5 Diphenylgu 0.5

To a portion A, is added 2 quarts of tri-a-naphthyl borate inaccordancewith the invention. -To

another portionB, which serves for comparison,

nothing is added. The trij-a-naphthyl borate is made by any well knownprocess of forming a boric acid ester of alpha naphthol.

Not only the tri-a-naphthyl borate maybe emment is frequently attendedwith an objectionat 141. They are then aged in a Pierer bomb for 2 daysat 70 under an oxygen pressure of 300 lbs. per square inch.

The material A then possesses a tensile'strength at break of 111 kilog.per sq. cm. and an elongation at break of 540% and it is not appreciablydiscoloured. The material B is completely degene erated- The productsobtained by the process of our invention are very resistant to ageingand do not suffer from discoloration. Moreover, our antiw agers do notvolatilize readily and therefore no losses byvolatilization take placeduring the milling of the mix or subsequent treatment, and the rubber,therefore, obtains the full benefit of the anti-ager." r

Since many embodiments of this invention, differing widely in one ormore respects, may be made without departing from the spiritof ourinvention, it is to be understood that we do not limit ourselves totheforegoing examples or description except as indicated in thefollowing claims:

and discoloration due to ageing which comprises incorporating withtherubber or rubber-like substances tri-a-naphthyl borate.

3.;The process of increasing the resistance of vulcanized rubber and.the like to deterioration and discoloration due to ageing whichcomprises incorporating'with the rubber or rubber-like substancestri-b-naphthyl borate.

4. Vulcanized rubber or rubber-like substances produced by the processset forth inclaim 1.

ployed, but the boric acid ester of betanaphthol may be employedaccording to forth in the example.

The two preparations are the procedure set cured for 45 minutes

